Our reason has this peculiar fate that, with reference to one class of its knowledge, it is always troubled with questions which cannot be ignored, b… - Immanuel Kant

He [Jesus] combines all duties (1) in one universal rule (which includes within itself both the inner and the outer moral relations of men), namely: Perform your duty for no motive other than unconditioned esteem for duty itself, i.e., love God (the Legislator of all duties) above all else; and (2) in a particular rule, that, namely, which concerns man’s external relation to other men as universal duty: Love every one as yourself, i.e., further his welfare from good-will that is immediate and not derived from motives of self-advantage. These commands are not mere laws of virtue but precepts of holiness which we ought to pursue, and the very pursuit of them is called virtue. Accordingly he destroys the hope of all who intend to wait upon this moral goodness quite passively, with their hands in their laps, as though it were a heavenly gift which descends from on high. He who leaves unused the natural predisposition to goodness which lies in human nature (like a talent entrusted to him) in lazy confidence that a higher moral influence will no doubt supply the moral character and completeness which he lacks, is confronted with the threat that even the good which, by virtue of his natural predisposition, he may have done, will not be allowed to stand him in stead because of this neglect (XXV, 29).

In the natural state no concept of God can arise, and the false one which one makes for himself is harmful. Hence the theory of natural religion can be true only where there is no science; therefore it cannot bind all men together.

Inexperienced in the course of world affairs and incapable of being prepared for all the chances that happen in it, I ask myself only 'Can you also will that your maxim should become a universal law?' Where you cannot it is to be rejected...